A Researcher Studies Normal Human Fibroblast Cells

Multiple Choice

A researcher studies normal human fibroblast cells.They can be maintained in culture but die off after about 30 cell generations.Unexpectedly, a colony of cells continues to survive and divide past 30 generations.Which scenario is most likely true for these cells?

A) DNA polymerase is constantly active.
B) The mismatch repair system is extra efficient.
C) The telomerase gene is being expressed.
D) Primase is able to extend the telomeres.
E) The cells do not need the ends of their chromosomes.